Mobile undersea habitat and method of use thereof



Feb. 17,1970 G. H. FAHLMAN ETAL 3,49 56 MOBILE UNDERSEA HABITAT AND METHOD OF USE THEREOF I med Nov. 5. 1968 2 Sheets-Sheet 1 ATTORNEYS Feb. 17, 1910 3,495,562

I MOBILE UNDERSEA HABITAT AND METHOD USE THEREOF a. H. FAHLMAN ET Al.

2 Sheets-Sheet 2 Filed Nov.

M RM 5 ma Mm m m n MY WA M 7 wr f 3 q l l lfl l lnu United States Patent 3,495,562 MOBILE UNDERSEA HABITAT AND METHOD OF USE THEREOF Gosta H. Fahlman, Kailua, and Henry M. Horn, Honolulu, Hawaii, assignors to Makai Range, Inc Waimanalo, Oahu, Hawaii, a corporation of Hawaii Filed Nov. 5, 1968, Ser. No. 773,524 Int. Cl. B63b 3/13; B63g 8/22 US. Cl. 114-16 Claims ABSTRACT OF THE DISCLOSURE An undersea habitat includes a main habitat assembly athwart a pair of spaced approximately parallel hulls which serve as ballast tanks and surfaced flotation. The structure is adapted to be towed to a diving site, and submerged at the diving site to provide life support for divers.

This invention relates to a mobile undersea habitat adapted to provide life support for divers during extended periods of undersea exploration, research, construction or other activities, as well as for decompression. The concept of providing such a life support is well known, as are its advantages over surface support systems which require extensive surface support facilities for frequent returns of the divers to the surface.

In one type of operation of undersea habitat, it is desirable to tow or otherwise move the habitat along the surface of the ocean so that the habitat can be readily moved from a base station to a diving area and vice versa. It is particularly advantageous for this type of operation that the habitat have good surface stability, so that it may be towed or propelled during rough weather. For this purpose, it is very desirable that, at least during the movement of the habitat along the surface, the habitat have a very substantial positive metacentric height. In order to achieve this objective, the habitat, according to the present invention, employs a catamaran structure, with the main portion of the habitat being mounted athwart of a pair of parallel pontoon structures which also serve as ballast tanks. The major portion of the main habitat structure is above the pontoon structure, so that it is readily serviceable afloat and so that the submerged center of buoyancy is above the center of gravity. The surfaces of the habitat are designed to readily shed water, so that the combination of the water shedding characteristics and large metacentric height gives the vessel excellent sea-keeping qualities.

According to another feature of the invention, the main habitat structure is recessed vertically into the pontoon hulls, so that as a result of the athwartship mounting of the main habitat structure, the loss of bull water plane area during the interface stages of submergence and emergence of the vessel is counteracted at least in part by an increase in water plane area at the main habitat structure. This structural feature increases the stability of the vessel during the critical stages of submergence and emergence. In addition, the vessel is provided with thwartship bridges between the pontoons, the bridges being elevated so that their center line is at the top of the pontoon hulls. The main portion of the habitat, the bridge tubes and the gas cylinders and other apparatus are mounted to provide a moment of inertia of the water plane area during the critical period of submergence and emergence that is adequate to maintain a metacentric height that is adequate to maintain stability during this critical period. As a result of this structure, further submersion by flooding the pontoons results in a lowering of the center of gravity and a raising of the center of buoyancy so that the stability of the vessel is further increased.

3,495,562 Patented Feb. 17, 1970 "ice In order that the invention may be more clearly understood, it will now be described with reference to the accompanying drawings, in which:

FIG. 1 is a simplified perspective diagram of the basic components of the mobile undersea habitat according to the invention;

FIG. 2 is a cross-sectional view of the undersea habitat of FIG. 1 taken along the lines 2-2;

FIG. 3 is a cross-sectional view of the undersea habitat of FIG. 1 taken along the lines 3-3;

FIG. 4 is a top view of a preferred embodiment of a mobile undersea habitat according to the invention;

FIG. 5 is a side view of the habitat of FIG. 4; and

FIG. 6 is an end view of the habitat of FIG. 4.

Referring now to the diagrams, and more in particular to FIG. 1, therein is illustrated a mobile underseas habitat including a main habitat structure, including a generally spherical diving compartment 10, a cylindrical living compartment 11, and a cylindrical laboratory compartment 12. The three chambers are positioned along a common axis, with a pressure lock 13 between the diving compartment 10 and living compartment 11, and a pressure lock 14 between the diving compartment 10 and the laboratory compartment 12. This arrangement permits the three compartments to be operated independently, and thus facilitates adapting the habitat to any desired mode of operation. While the selection of three independent compartments is advantageous for particular diving operations, it is not intended that the invention be limited to this particular number and configuration of compartments. It is pointed out, however, that the provision of two compart- I ments is a minimum from the standpoint of safety of the divers. As is the usual case in underseas habitat strucseparate compartments may be controlled independently, to facilitate use of the chambers for research or development projects or in emergency situations.

The main purpose of this portion of the undersea habitat is to provide divers with a housing which is maintained at high hyperbaric pressure, or at ambient pressure, as desired. As an example of typical outfitting of the three compartments, the diving compartment 10 may include controls for lowering of the vessel, the living compartment 11 may include equipment such as bunks, tables, chairs, and other facilities for the divers, and the laboratory compartment may include galley equipment, electrical and medications system control, and research equipment.

The main habitat structure, consisting of the chambers 10, 11 and 12, is mounted athwart a pair of approximately parallel spaced-apart pontoon structures 15 and 16 at a point intermediate to the ends of the pontoons 15 and 16, preferably at the center of the vessel. In other words, the axis of the main habitat structure extends normal to the verticle planes extending through the axes of pontoons 15 and 16. In addition, the main habitat structure is recessed vertically in the pontoons 15 and 16, as is shown more clearly in FIG. '2. As pointed out above, this feature is provided so that the loss of water plane area on the pontoons during the initial stages of submergence and last stages of emergence are compensated in part by an increase in water plane area on the surfaces of the main habitat structure, so that the stability of the vessel is increased during this critical period. It is apparent that the athwartships mounting of the main habitat structure is particularly desirable from the standpoint of the increase in the moment of inertia of the water plane area.

The catamaran pontoons 15 and 16, in addition to serving as a platform for the main habitat structure, constitute the hulls of the vessel, thereby giving the vessel good stability on the surface, and providing it with good towing characteristics. In addition, the pontoons serve as a foundation for the vessel when it is submerged to the sea floor, and, as will be disclosed in more detail in the following paragraph, they serve as the main ballast tanks of the vessel.

. While it is possible to provide the pontoons and 16 with propulsion devices, it is preferred that any major propulsion system be omitted, so that movement of the vessel at the surface is dependent upon a more eflicient and dependable surface towing arrangement. It may be desirable, of course, to provide small thrusters on the pontoons to facilitate positioning of the vessel at the diving site. Therefore, according to the preferred aspects of the invention, the pontoons are sharped for minimum costs, maximum strength, optimum venting of entrapped air, and have bow shapes that are adequate for hydrodynamic lift of the bows while under way. It is preferred that the bow shapes of the pontoons be somewhat blunt so that during towing they force the bow wave intersect forward of the deck structure of the vessel, so that the seas are damped under the deck structure between the hulls. The deck structure itself will be described in more detail in the following paragraphs.

Referring now to FIGS. 1 and 3, the forward and aft ends of the pontoons 15 and 16 are joined by bridge tubes 17 and 18 respectively. The bridge tubes 17 and 18 are designed to provide the necessary torsional, vertical and horizontal structural strength to the assembly, and their cylindrical cross-section, which may be, for example, 3 to 4 feet in diameter, minimizes torsional strain of the structure. In addition, the bridge tubes 17 and 18 may be employed as auxiliary ballast compartments when re quired for additional payload submerged.

As shown in FIG. 2, the diving compartment 10, living compartment 11, and laboratory compartment 12, are provided with diver entry and exit ports 19, 20 and 21 respectively extending from their lower surfaces. In addition, the pontoons 15 and 16 are provided with ports 22 and 23 on their lower surfaces for purposes of flooding and blowing out the pontoons, and the bridge tubes 17 and 18 are also provided with openings in their lower surfaces to permit flooding and blowing out. Thus, as shown in FIG. 3, the aft bridge 18 is provided with an opening 24 in its lower surface, and a similar opening is provided (not shown) in the forward bridge tube 17.

A preferred embodiment of the mobile undersea habitat according to the invention is illustrated in FIGS. 4 through 6. As illustrated in these figures, a deck structure is provided above and extending between the catamaran pontoons 15 and 16. The deck structure 30 is preferably made from a plurality of expanded metal panels in order to provide good water shedding characteristics and minimum vertical resistance, and yet permit the movement of personnel on the deck structure when it is above as well as below the surface of the water. Gas cylinders 31 are mounted in a framework 32 below the deck panel in such a vertical plane as to maximize moments of inertia of the water plane area with the tops of the hulls awash. These gas cylinders are provided in order to supply the gas pressures to the pontoons 15 and 16 and the bridge tubes 17 and 18. Suitable connections (not shown) are provided between the gas cylinders and the diving chamber in order to permit divers to control the application of pressure to the pontoons and bridge tubes. In addition, electrical supply in the form of sealed batteries, fuel cells, or nuclear power plants, may be also mounted in or on the deck panel. Additional life support equipment (not shown) may be mounted below the deck panels or at other 10- cations on the vessel. If desired, towable escape capsules 33 may be mounted on the forward and aft portions of the deck structure.

A weight 35 of, for example, 3 tons (submerged) is suspended under the vessel by means of a cable 36, and is adapted to be raised and lowered by means of a winch 37. The function of this weight will be described in more detail in the following paragraphs.

Each of the pontoons 15 and 16 is preferably divided into a plurality of compartments, for example five compartments 40, 41, 42, 43 and 44, as shown in dash lines in FIG. 5. The center compartment 42 of each pontoon is preferably a variable ballast tank. The variable ballast tanks are supplied with high pressure air from the gas cylinders to the top of these compartments by means of, for example, two-inch lines (not shown). Water is discharged and taken on by these variable ballast tanks through the openings in their lower surfaces, as shown in FIGS. 2 and 3. (Each of the compartments of each of the pontoons 15 and 16 is provided with a similar opening in its lower surface.) The variable ballast tank of each pontoon is also provided with means for venting through the air supply lines. The remaining compartments of each pontoon are the main ballast compartments and are freely flooded through the openings in the bottom surfaces. These compartments may be blown with air pressure from the gas cylinders 31 by means of suitable lines (not shown). In addition, vents may be located in the forward and aft end of each of these compartments, and connected to a manifold for central operation from the diving compartment 10, or externally from a location on deck.

In a satisfactory embodiment of the mobile undersea habitat according to the invention, the vessel has a metacentric height of approximately 25 feet in the surfaced state. At the critical point of submergence or emergence, the combination of the main habitat structure, gas cylinders and bridge tubes provide a moment of inertia to the water plane area adequate to maintain a metacentric height of 2 feet. Upon further submersion, the center of gravity was lowered and the center of buoyance was raised so that a submerged center of buoyance of about 5 feet above the center of gravity was obtained. These values provide ample stability for the vessel. The bridge tubes 17 and 18 were designed to withstand an internal pressure slightly in excess of maximum depth pressure, so that when pressurized, they provide additional submerged re serve buoyance.

In the preferred method of operation of the undersea habitat according to the invention, the vessel is first towed to the diving site by means of another vessel. The hulls are then flooded. At this time, the vessel has a positive buoyancy of, for example, 10 tons. Divers who are on board the habitat during the submergence procedure may enter the vessel either before it leaves the port, or when it reaches the diving site. The main habitat structure is pressurized before submergence, with the divers on board. At the diving site, the divers release the diving weights 35 so that they drop, for example, 50 feet below the undersea habitat. At this time, the habitat still has a positive buoyancy.

The occupants of the habitat then open the vents for the variable ballast tanks, to provide a negative buoyancy of, for example, 2 tons. The habitat then starts to sink. When the weights 35 hit the ocean floor, the buoyancy of the vessel becomes positive by, for example, approximately 1 ton. The divers then operate the winch 37 in order to pull the habitat to the ocean floor. When the vessel reaches the ocean floor, the remaining ballast tanks are opened, to provide the vessel with a negative buoyancy of, for example, 10 to 20 tons. At this time, the divers also lock the winch, and pressurize the diving compartment to ambient sea pressure. The divers then depart from the habitat, to perform their mission on the sea floor.

The submergence of the vessel is preferably controlled, for example, by means of one or more cables or chains extending from the surface to the ocean floor, to serve as guide lines, with suitable lines on the habitat vessel being aifixed to eyes which surround the guide line and cables. Either taut moored buoys or a surface vessel may be used to secure to the surface.

In order to raise the undersea habitat to the surface, the divers return to the pressure chamber, and close the hatch, and start to blow out water from the ballast tanks. This will provide a positive buoyancy of, for example, up to 10 tons. The habitat will then rise to the surface, at which time its remaining ballast tanks (the pontoons) are blown out to obtain full towing buoyancy for surfaced towing. The habitat is then towed back to port.

The divers remain in one or all of the compartments at the port while it is being depressurized, either from its own gas supply or from a shore based supply. During decompression, the onboard external facilities may be refitted for another diving operation.

What is claimed is:

1- A mobile undersea habitat comprising a main axially extended habitat structure, a pair of parallel spaced apart pontoons, said main habitat structure being mounted athwart said pontoons and vertically recessed therein, whereby the loss of moment of inertia of the water plane area of said pontoons during submergence of said vessel is at least partly compensated by increase in the moment of inertia of the water plane area on said main habitat structure, said pontoons providing floatation for raising the habitat clear of the water when blown.

2. The habitat of claim 1 wherein said main habitat structure comprises a central diving compartment, and a pair of separate compartment affixed to opposite sides of said central compartment by pressure hatch means,

said separate compartments being affixed to and vertical- *ly recessed in separate pontoons.

3. The habitat of claim 1 comprising separate bridge tube means joining said pontoons, said bridge tube means comprising auxiliary ballast tanks and additional moment of inertia of the water plane area during interface operation.

4. The habitat of claim 1 comprising weight means, and winch means operably mounted on said habilat for raising and lowering said weight.

5. The habitat of claim 1 comprising deck means extending between said pontoons fore and aft of said main habitat structure, and gas cylinder means for said ballast tanks and for internal diver breathing gas positioned between said pontoons, and so orientated asto maximize moment of inertia of the waterplane area when the tops of the pontoons are at sea level.

References Cited UNITED STATES PATENTS 3,335,684 8/1967 Trippel l1416 3,413,947 12/1968 Picard 11416 TRYGVE M. BLIX, Primary Examiner 

